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  • Genetics
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  • Strömungsmechanik
  • Wiley-Blackwell  (140)
  • Georg Thieme Verlag
  • Sage Publications
  • 1980-1984  (140)
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  • Wiley-Blackwell  (140)
  • Georg Thieme Verlag
  • Sage Publications
  • Springer  (45)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 1-25 
    ISSN: 0192-253X
    Keywords: maize ; endosperm ; mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 3
    ISSN: 0192-253X
    Keywords: gonad differentiation ; gene expression ; two-dimensional micro gel electrophoresis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Gonadal protein patterns were studied during development in the rat by two-dimensional micro-gel electrophoresis. Specific proteins were detected in both the male and the female sex at the morphologically indifferent state (two female- and one male-specific) and during differentiation. At the onset of gonadal differentiation (day 14) two additional sex-specific proteins were discovered in the male and two in the female. These proteins remained expressed during further development. One testicular protein was restricted to the cytosol of the tunica albuginea. The other one was absent from the tunica. In the female gonad, the two proteins were membrane-specific, one present in germ cells, the other in somatic cells. In the testis, one additional protein was discovered at postnatal day 1. Thus according to biochemical criteria there is no indifferent state of gonadal development. The testis and ovary express sex-specific genes both before and after the onset of gonadal differentiation.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 65-71 
    ISSN: 0192-253X
    Keywords: BrdU ; rDNA ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We demonstrate that Bromodeoxyuridine (BrdU)-induced reductions of the ribosomal RNA cistrons (rDNAs) are observed in Drosophila virilis, and Drosophila busckii, but not in karyotypically normal adults or larvae of Drosophila melanogaster. However, BrdU does reduce the redundancy of the rDNAs of XO D melanogaster males, in which a compensatory response is evidenced in the untreated XO sibling controls. These results suggest that the BrdU-rDNA interaction is specific to events which modulate rDNA redundancy. Further, both thymidine and deoxycytidine “reverse” the BrdU effect in D virilis, an observation which is inconsistent with current working hypotheses describing the mechanisms of BrdUs effects.
    Additional Material: 3 Tab.
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  • 5
    ISSN: 0192-253X
    Keywords: pattern formation ; cell-lethal mutations ; imaginal discs ; cell death ; pattern triplications ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects of 48-hr 29°C temperature treatments on the imaginal leg discs of Drosophila hemizygous for a temperature-sensitive cell-lethal mutation were examined to determine whether the induction of patches of cell death in the imaginal discs is a prerequisite for the induction of pattern triplications. In a statistical analysis, the frequency of induction of cell death was found to be highly correlated with the frequency of induction of triplications. In addition, individual discs in which cell death had been induced were cultured and found to triplicate at frequencies significantly greater than discs with no visible cell death, or unselected discs from the same larvae.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 7
    ISSN: 0192-253X
    Keywords: Drosophila melanogaster ; ts-mutants ; adenylate cyclase ; Phosphodiesterase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The mode of the developmental expression of adenylate cyclase (AC) and phosphodiesterase (PDE) in D melanogaster indicates that PDE plays the major role in the maintenance of a certain level of cAMP in postembryonic development, while both enzymes function in concert in imago. The ts-mutants ts155 and ts622, characterized upon their isolation as having an increased cAMP content and normal PDE activity, manifest high levels of AC activity from the third day of imago life. The levels of PDE activity characteristic for adult mutants with altered enzyme activity (low in ts66 and ts980, high in ts398) are manifested in ts980 from larval instar II, and from the larval instar III in ts398 and ts66. Data on the dependence of PDE activity in adults upon temperature of incubation, being in agreement with the expectations for a ts-mutation in a gene coding for a form of PDE in case of ts66, suggest that ts398 affects not the enzyme-coding gene but rather one for an activator protein. The fact that in ts398 (the polyphasic ts-lethal mapping to 1-38.9) 1) AC activity is somewhat higher than normal at 22°C and is readily activated at 29°C, 2) activity of PDE-I assayed in heat-pretreated homogenates is higher than normal, 3) that boiled extracts of ts398 are potent activators of the wild type and of its own PDE-I indicates that it is a mutation affecting calmodulin, which is known to be stable at boiling and capable of activating both AC and PDE-I. Data on Ca2+ and EGTA effects suggest that the mutation presumably increases Ca2+-binding activity of calmodulin, ts980 and ts622, in which ts-lethality could be produced only by certain doses of haloperidol and triftazine, appear to be lethal in compounds with ts398, thus indicating that these mutations could affect the same calmodulin-controlling gene.
    Additional Material: 6 Ill.
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  • 8
    ISSN: 0192-253X
    Keywords: actin ; gene regulation ; development ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Extreme and rapid changes in the synthesis of messenger RNAs and proteins accompany differentiation in wing tissues of Drosophila. Of the six actin genes, at least three are expressed in wing cells, some during the most extreme changes in cell shape. However, different messages of the set appear, decay, and reappear on a regulated temporal program. These results show that actin expression is stage-specific in a single cell type.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 243-244 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 239-239 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 11
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 43-58 
    ISSN: 0192-253X
    Keywords: ciliate genetics ; Tetrahymena malaccensis ; karyonidal inheritance ; macronuclear assortment ; selfing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type determination in Tetrahymena malaccensis is karyonidal, ie, the four new macronuclei developing in a single conjugating pair are independently determined as to which of the six known mating types they will express. Occasional selfing clones are similar to those in T thermophila, in that any one is capable of stabilizing at a restricted range of mating types. The genetic basis of mating type potentialities is incompletely resolved. T malaccensis may, like T thermophila and T canadensis, have a single multiallelic locus that controls the array of types. Quantitative considerations suggest, however, that other loci may be involved.
    Additional Material: 1 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 14
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 83-91 
    ISSN: 0192-253X
    Keywords: temporal genes ; acid hydrolases ; liver ; mice ; hepatocytes ; nonhepatocytes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cell specificity of expression of three distinct trans acting temporal gene systems determining the developmental control of α-galactosidase, β-galactosidase and β-glucuronidase was tested in mouse liver. For α-galactosidase and β-galactosidase, expression was limited to hepatocytes; no effect was seen in nonhepatocytes. For β-glucuronidase the data suggest that expression of the Gus-t temporal locus is also limited to hepatocytes, and that the smaller enzyme reduction seen in nonhepatocytes of some strains is due to a separate systemic regulatory locus that is also present in the [Gus] gene complex. We conclude that the temporal gene-determined timing mechanisms initiating switches in rates of enzyme synthesis are intrinsic to the cells themselves and are not communicated to adjacent cells. This conclusion applies to the temporal locus for β-glucuronidase that is proximate to its structural gene as well as those for α-galactosidase and β-galactosidase that are distant from the structural genes that they regulate.
    Additional Material: 5 Tab.
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  • 15
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 16
    ISSN: 0192-253X
    Keywords: Tetrahymena ; Paramecium ; mating type differentiation ; intranuclear coordination ; macronuclear molecular cloning ; ARF ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type determination in Tetrahymena thermophila involves developmentally programmed, heritable alterations of the macronucleus, localized to the mtd locus. This determination can be predictably controlled by the environmental conditions during macronuclear development, eg, temperature and time of refeeding. In this article we have further characterized the effects of delayed refeeding on mating type determination, as revealed by the frequency of mating types among the progeny of a cross. Our results show that 1) the magnitude of this starvation effect decreases with temperature of conjugation and becomes undetectable at 18°C; 2) starvation during the interval 14 to 22 hr (after conjugation is induced at 30°C) is a necessary and sufficient condition for the induction of starvation effects; 3) relative mating type frequencies vary monotonically with nutrient concentration present during this critical period; and 4) sister macronuclei, developing under starvation conditions in the same cytoplasm, differentiate majority mating types characteristic of early or late refeeding; sister macronuclei show no apparent correlation with each other. On the basis of our observations on early and late refed cells, we propose that the composition of the newly developed macronucleus is the outcome of two key events: 1) mating type determination at the mtd locus and 2) differential molecular cloning of generally one or two autonomously replicating fragments (ARFs) of the macronuclear DNA bearing the mtd locus.
    Additional Material: 5 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 177-177 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 201-207 
    ISSN: 0192-253X
    Keywords: rDNA ; compensation ; rRNA-DNA hybrids ; restriction analysis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The compensatory response is a regulatory event influencing the redundancy of the ribosomal RNA cistrons (rDNAs) of Drosophila melanogaster. In this report we attempt to demonstrate that the compensatory event and the thymidine analogue bromodeoxyuridine (BrdU) specifically interact. We conclude that the drug inhibits the compensatory response of Drosophila melanogaster XO males and argue that the compensatory event is not the passive consequence of replicational dominance known to occur in Drosophila polytene tissues.
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  • 19
    ISSN: 0192-253X
    Keywords: centriole ; mitotic center ; myxomycete ; Physarum ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Amoebae of the Myxomycete Physarum polycephalum in the interphase state typically contain only one proflagellar apparatus in which the anterior kinetosome (anterior centriole) is attached to the microtubule organizing center 1 (mtoc 1). We built strains possessing more than one mtoc 1 and a variable number of anterior centrioles to allow the appearance of new structures. In 8% of the amoebae of these strains, the 1:1 attachment between the anterior centriole and the mtoc 1 is not always respected. In nine cases studied using tridimensional reconstructions from ultrastructural thin sections, the pattern of attachment was more complex. A mtoc 1 could be linked to several anterior centrioles, and/or reciprocally an anterior centriole could be linked to several mtoc 1. In one case, an anterior centriole was not linked to a mtoc 1 and in three cases, a single centriole exhibited anterior and posterior characteristics. These observations suggest that (1) each pair of centrioles constitutes a morphological and physiological entity that is distinct from the mitotic center (mtoc 1); (2) the attachment of the anterior centriole to the mtoc 1 occurs at the end of each mitosis; (3) there is an inductory process during the morphogenesis of the link between the anterior centriole and the mtoc 1; (4) the anterior characteristics of a centriole can be present in the absence of the link with the mtoc 1; (5) the anterior and posterior characteristics of a centriole are not exclusive of each other, ruling out the existence of a lineage corresponding to the anterior centriole and a lineage corresponding to the posterior centriole; and (6) the differences between anterior and posterior centrioles result from a maturation process.
    Additional Material: 3 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 63-63 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 21
    ISSN: 0192-253X
    Keywords: axolotl ; isozymes ; phosphoglucomutase ; esterase ; G-K mapping ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four isozyme systems were surveyed in our laboratory-bred colony of axolotls (Ambystoma mexicanum) to determine whether there were elecrophoretic variants that could be used as markers in developmental experiments. For malate dehydrogenase (MDH), lactate dehydrogenase (LDH), and phosphoglucomutase (PGM), the best separations were obtained by isoelectric focussing on polyacrylamide slab gels, whereas for soluble esterases (Est), conventional polyacrylamide gel electrophoresis was used. The patterns for both MDH and LDH were consistent with two-locus models, but no variation was obtained. The results for PGM support a single-locus model with two alleles that are expressed codominantly in heterozygotes. There is also evidence for a third, null allele. The pgm gene maps approximately 24 map units from its centromere. The majority of the animals tested produced four esterase bands. We propose that each is controlled by a separate locus. One of the bands, Est-3, is absent in some animals. The results of various crosses support the proposition that these animals are homozygous for a null allele. The est-3 gene is distant from its centromere.
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 103-114 
    ISSN: 0192-253X
    Keywords: Drosophila ; pupation ; larval moults ; Lethalcryptocephal ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The events of normal pupation in Drosophila melanogaster are described in detail from the time of gas bubble expulsion until the completion of pupation with the eversion of the cephalic complex. The importance of the internal gas bubble for posterior movement of the prepupa is examined and its relation to the expulsion of the larval mouthparts and the creation of the anterior gas space described.The phenotype of lethalcryptocephal homozygotes, which characteristically cannot evert their heads, is re-examined. Observations of larval lethality and multiple mouthparts in 1 (2)crc larvae and pupae are described. These new aspects of the mutant phenotype are discussed with respect to the abnormalities of pupation. Fristrom's hypothesis that the basic mutant lesion is an increased stiffness of the pupal cuticle due to an excess chitin deposition is re-evaluated.
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  • 23
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 24
    ISSN: 0192-253X
    Keywords: temporal-regualatory variation ; isocitrate dehydrogenase ; rainbow trout ; Salmo gairdneri ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We examined a temporal series of embryos from 14 full-sib families of rainbow trout with starch gel electrophoresis to determine the time of initial detection of enzyme produced by ldh-3. Maternal enzyme was detected in unfertilized eggs, whereas paternal alleles showed evidence of initial expression after gastrulation and epiboly. Two alleles, 40 and 71, were expressed synchronously several days before the 114 allele. Measurement of enzyme activity by spectrophotometric analysis and serial dilution supported these observations. The degree of delay of expression of the 114 allele between families was coupled with other estimates of developmental rate. These data suggest the existence of allelic variation at a cis-acting genetic element controlling the pattern of ontogenetic expression of structural alleles at Idh-3.
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  • 25
    ISSN: 0192-253X
    Keywords: avian developmental antigens ; hybrids ; erythroid subpopulations ; species restriction ; monoclonal antibodies ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Monoclonal and polyclonal antibodies were used to examine the expression of three erythroid developmental antigen systems in the chicken, Japanese quail, and quail-chicken hybrid. Chicken fetal antigen (CFA), quail fetal antigen (QFA), and chicken adult antigen (CAA) each represent a series of cell-surface glycorproteins associated with the development of avian hematopoietic cells. Monoclonal anti-CFA antibodies from clones 190-4 and 288-1.1.1.2 supernatants were shown to react against epitopes associated with CFA determinants 8 and 2, respectively. Using complement-mediated microcytotoxicity, these reagents permitted the identification of different erythroid subpopulations in the neonatal chicken and hybrid; therefore, heterogeneity in cell surface CFA determinants among mature peripheral erythrocytes should serve as a useful tool for analyzing erythroid development. In the case of CAA, erythrocytes from adult hybrids were found to express the same complement of CAA determinants identified in the chicken, and CAA appeared much earlier in the hybrid than in either of the parental species. Similarly, two species-restricted fetal antigens associated with similar glycoproteins, CFA8 and QFA, had similar developmental profiles in their respective species, the chicken and quail. In contrast, these antigens were dominantly expressed but exhibited different developmental profiles on erythrocytes from the hybrids. While quail-chicken hybrids exhibited apparent genomic interactions in the expression of these developmental antigens, no evidence for the existence of hybrid-specific fetal antigens was obtained.
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  • 26
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 5 (1984), S. 179-180 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 27
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 28
    ISSN: 0192-253X
    Keywords: chick blastula ; epiblast-hypoblast interaction ; protein pattern ; primitive streak induction ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The patterns of protein synthesis are examined in the hypoblast and in the areas that comprise the epiblast, that is, the area opaca, the marginal zone, and the central area, during the blastula stage which marks the beginning of the interaction between the epiblast and hypoblast for induction of the primitive streak. The results demonstrate that there are distinct qualitative and quantitative differences in protein patterns in individual areas of blastoderm, the differences being most distinct between the hypoblast and any of the component areas of the epiblast. These differences in patterns of proteins suggest that the component areas of the chick blastula have already diverged to different developmental fates before any apparent morphogenetic differentiation, that is, the appearance of the primitive streak.
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  • 29
    ISSN: 0192-253X
    Keywords: 5S ribosomal RNA genes ; rearrangement ; macronuclear development ; macronuclear replication ; Tetrahymena thermophila ; determination ; phenotypic assortment ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of the 5S rRNA genes in the MACronuclear genome of Tetrahymena thermophila was examined during MAC development and replication. The 5S genes are arranged in several tandem arrays of alternating transcribed and spacer sequences in both MICronucleus and MAC. The number of EcoRI fragments bearing 5S gene clusters is similar in MIC and MAC. Most fragments occur in both the MIC and newly formed MAC genomes, a few being MIC-limited and a few MAC-limited. The same rearrangements are seen in the MACs of all four caryonides of a mating pair, and most rearrangements are seen in the newly formed MACs of different inbred strains. During replication of the MAC about half the fragments bearing 5S gene clusters disappear in different cell lines, and new fragments containing 5S genes appear. These fragments differ in size from those present in the MIC or newly formed MAC. These alterations occur in the MACs of all strains except strain B, which is more resistant to vegetative rearrangement. The losses and gains of fragments occur during clonal propagation of cell lines. The process begins by 35 fissions following conjugation, but once an alteration occurs, it is stably propagated. Clonal variation occurs with respect to which losses and gains occur, although a nonrandom distribution is seen among cell clones. We conclude that the alterations in MAC fragment size occur at two stages in the life cycle of Tetrahymena. The first stage occurs during conjugation, when the MAC develops from the MIC. The second stage becomes manifest during vegetative growth, when DNA replication occurs in the MAC and daughter molecules are distributed “amitotically” to daughter nuclei. The two-stage character to MAC alterations for the 5S genes is interpreted in terms of the two steps previously described for MAC differentiation: determination and phenotypic assortment. Possible molecular mechanisms are also discussed.
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  • 30
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 1-20 
    ISSN: 0192-253X
    Keywords: gene transfer ; mouse embryos ; genetic engineering ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 31
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 31-48 
    ISSN: 0192-253X
    Keywords: B cell development ; IgM ; mouse ; tumor metastasis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The regulation of IgM expression was studied in clones derived from a murine B lymphocyte cell line, WEHI279.1. During normal B cell development IgM heavy chain synthesis increases concomitantly with heightened IgM secretion and reduced cell-surface IgM. However, in these subclones, the levels of membrane-bound and secreted IgM were regulated independently of one another. The amount of IgM secreted by the cells was tightly coupled to the amount of heavy chain synthesis, suggesting that the major control of secretion is pretranslational. Surface IgM exhibited a more complex regulation, with both pre- and posttranslational components. Variation in the expression of both forms of IgM occurred at high frequency. Although IgM expression follows a unidirectional pathway in nontransformed cells, the variability in these tumor cells was reversible and cellautonomous. High levels of phenotypic variability may be important in the ability of transformed cells to escape the immune response.
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  • 32
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 69-76 
    ISSN: 0192-253X
    Keywords: Polysphondylium ; cellular slime mold ; microcysts ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutants were selected that are incapable of differentiating microcysts, a resting stage formed in response to high osmotic conditions. In the selection procedure amebae that failed to encyst were removed by flotation in 46% Percoll. Genetic crosses among 15 mutant strains were made by means of the macrocyst sexual cycle. Eleven of the strains mapped to three loci. Mutations at two of these loci (cysA and cysB) produced no observable alteration in the aggregation-fruiting pathway, although one set of strains altered at the cysA locus carried defects at a second unlinked site which blocked aggregation. The single strain that defined the third locus (cysC) is aggregateless. These results confirm the conclusion that there are several genes whose function is essential to microcyst development and is exclusive to this pathway. It remains uncertain whether there are other genes whose action is crucial to both encystment and to aggregation/fruiting.
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  • 33
    ISSN: 0192-253X
    Keywords: Physarum polycephalum ; differentiation ; food supply ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of food supply on the onset of asexual and sexual plasmodium formation in Physarum polycephalum was studied. Asexual differentiation occurs readily in amoebae carrying the matAh mating type allele. The density at which these amoebae begin to differentiate is influenced by the ind locus, which controls the production of a diffusible inducer. The alleles ind-1 and ind-2 are known. Strains carring the ind-1 allele begin plasmodium formation at a low amoebal density (rapid differentiation), while strains carring the ind-2 allele differentiate at a higher amoebal density (slow differentiation). The onset of differentiation is characteristic of the strain and did not change with a 20-fold variation in the number of food bacteria available. Sexual differentiation occurs between compatible amoebal strains. For a given pair of amoebal strains the onset of plasmodium formation occurs at a characteristic cell density that is determined by the genetic backgrounds of the strains. The ind locus is one of the genes that influences this cell density. Plasmodia are formed at a lower cell density in crosses involving compatible amoebae carrying the ind-1 allele than they are in crosses with strains carrying the ind-2 allele. As was found for asexual differentiation, an approximate 20-fold variation in the food supply did not affect the initiation of sexual plasmodium formation. These results suggest that in most cases starvation does not trigger the differentiation of amoebae into plasmodia. The time of onset of plasmodium formation is determined largely by genetic factors.
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  • 34
    ISSN: 0192-253X
    Keywords: cytokin mutant ; habituation ; Nicotiana ; tissue culture ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cultured leaf tissues of Nicotiana tabacum L. cv. “Havana 425” normally require an exogenous source of cytokinin for rapid growth; stem-cortex tissues do not - ie, they exhibit the cytokinin-habituated phenotype. We found that plants regenerated from cloned cortex and leaf tissues from one particular plant differed in leaf-tissue phenotype: Leaf tissues derived from leaf cells exhibited the normal, nonhabituated phenotype, whereas leaf tissues derived from cortex cells were cytokinin-habituated. This difference in leaf phenotype was not found using leaf and cortex cells from six other donor plants. The inheritance of the habituated leaf trait was studied in tissues from cortex-derived plants and hybrids between these plants and normal plants. F1 hybrids were intermediate between the parental types in degree of habituation. No differences were found between reciprocal hybrids. These results suggest that the habituated leaf trait is an incompletely dominant, nuclear trait. Both parental and intermediate phenotypes were recovered in the F2 progeny. The frequency of habituated leaf progeny in the F2 and backcross populations provide evidence that the trait is regulated at a single genetic locus.
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  • 35
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 159-165 
    ISSN: 0192-253X
    Keywords: trisomy ; monosomy ; aneuploidy ; chimeras ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mouse trisomy 15 ↔ 2n aggregation chimeras have been produced and analyzed at 19 days of gestation. We have found that these chimeras are viable and in most instances normal in external appearance, unlike trisomy (Ts)-15 embryos which are severely growthretarded and die midway through gestation. Trisomic cells were found in all tissues of fetal chimeras, with proportions not significantly different from those of the controls in kidney, heart, liver, and brain, but significantly reduced in thymus and spleen. Ts-15 cells do not, therefore, exhibit a proliferative advantage during fetal development of tissues susceptible to Ts-15-related lymphoid malignancies. However, the presence of Ts-15 cells in the placenta may be associated with placental overgrowth. One fetus containing a monosomy 3 cell population was also observed, the first term fetal chimera with monosomic cells that has been detected.
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  • 36
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 37
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 199-210 
    ISSN: 0192-253X
    Keywords: aging ; Drosophila ; behavior ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The question as to the role that genes play in determining life-span is essentially unresolved. Although it is well documented that genotype influences longevity, this is no way demonstrates that life-span is genetically determined. In the present study we examine five temperature-sensitive mutations for their effect on the aging process. At the permissive temperature (22°C ), the longevity of each mutant strain is comparable to that of wild type. However, at the restrictive temperature (29°C ) the life-span of these mutants is severely curtailed. Using behavior loss as a landmark of adult physiological age, we examined each of these strains for its pattern of behavior loss relative to longevity, and compared each to a wild-type strain. In four of the mutations the pattern of behavior loss relative to longevity was severely altered at one or both temperatures. However, one strain, adl-16tsl displayed a pattern of behavior loss that was indistinguishable from wild type at both 22°C and 29°C. At 29°C not only was the longevity decreased, the pattern of behavior loss was also compressed into a shorter time period. The compression of the pattern of behavior loss was proportional to the reduction in life-span. Thus it appears that this mutation, adl-16tsl, may accelerate the normal aging process when placed at 29°C. The potential utility of these types of mutants for studying the aging process is discussed.
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  • 38
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 231-231 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 39
    ISSN: 0192-253X
    Keywords: chimera ; cell interactions ; sex reversed ; sex determination ; melanocyte ; intersex ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The manufacture of mammalian chimeras by aggregating embryos of different genetic constitutions makes possible the study of the genetic control of cellular interactions during embryonic development. Several different chimeric combinations have been made to study the role of the sex-reversed mutation in gonadogenesis and in gametogenesis. Sex reversed directs the gonad to become a testis and thus renders a SxrXX mouse sterile since gonocytes with two X chromosomes cannot complete gametogenesis in a testis. However, SxrXX gonocytes in the ovary of a female chimera become normal oocytes. The competitive interactions of genetically different melanoblasts in populating hair follicles and of primordial germ cells in populating the gonad have been revealed in chimeras. Chimeras have also been used to rescue inviable teraploid embryos and to permit teteraploid cells to display their differentiative capacities in normal tissue environments. We conclude that the genotype affects the capacity of cells to elaborate and to respond to inductive stimuli at each step in differentiation. The fine tuning of cellular interactions becomes apparent in chimeras made from embryos of different genotype.
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  • 40
    ISSN: 0192-253X
    Keywords: marine molluscs ; heterozygosity ; growth ; selection models ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We examine several models that may account for the observation that in populations of marine molluscs in general, and of the American oyster (Crassostrea virginica) in particular, the growth of an individual is related to its degree of heterozygosity and, also, that the number of heterozygous individuals in the population is less than expected on the assumption of random mating and no selection. We classify these models into nonselective, selective, and mixed models. We conclude that mixed models are the most likely to apply to real populations, but cannot exclude selective models. Nonselective models appear least likely. Current evidence favors a model that assumes that heterozygotes enjoy a fitness advantage as adults, primarily because of their faster growth, and that the lower numbers of heterozygotes in the population result from some form of nonrandom fertilization. One possible source of nonrandom fertilization is variation in the time of spawning of individuals due to differences in body size.
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  • 41
    ISSN: 0192-253X
    Keywords: genetic variation ; molecular evolution ; natural selection ; DNA polymorphism ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The evidence for genetic variation can be traced to Mendel's experiments: The discovery of the laws of heredity was made possible by the expression of segregating alleles. Since that time, the study of genetic variation in natural populations has been characterized by a gradual discovery of ever-increasing amounts of genetic variation. In the early decades of this century geneticists thought that an individual is homozygous at most gene loci and that individuals of the same species are genetically almost identical. Recent discoveries suggest that, at least in outcrossing organisms, the DNA sequences inherited one from each parent are likely to be different for nearly every gene locus in every individual; ie, that every individual may be heterozygous at most, if not all, gene loci. But the efforts to obtain precise estimates of genetic variation have been thwarted for various reasons.
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  • 42
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 407-424 
    ISSN: 0192-253X
    Keywords: selection ; enzyme ; control-gene ; DNA polymorphism ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The control of alcohol dehydrogenase (ADH) activity in natural populations of Drosophila melanogaster is chromosomally diverse and due to variation in allotype, enzyme level, and possibly post-translational modification. A comparative study of evolution in Adh structural gene variations with those loci modifying ADH expression has been carried out in large model populations maintained in environments that varied in temperature and food. Broadly based measures of gene expression were obtained as ADH activity and ADH protein level (determined immunologically) from individual flies whose allotype was also determined. The response to selection by “regulatory” or modifier loci compared with ADH allotypes was found to vary with environment, and its direction was not necessarily predictable from the kinetic properties of allele products. Selection for dominance modification of ADH activity in relation to Adh allotype was also observed. Analysis of genotype-environment interaction discerned two main types of response. Two major classes of chromosomal types, identified from restriction endonuclease map variations in a 12-kb region of DNA containing the Adh transcriptional unit, were present in the population. These two types of chromosome were in turn associated with the two types of interaction between genotypes and the environment. The results implicate polylmorphism for the control of genotypeenvironment interaction in populations, a genetically complex unit of selection, and a degree of evolutionary independence between structural and regulatory genes.
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  • 43
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    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 44
    Electronic Resource
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    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 45
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 61-68 
    ISSN: 0192-253X
    Keywords: cell adhesion ; macromolecular ; sponge factors ; Dictyostelium ; adhesion-blocking antiserum ; staggerer mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cellular adhesion is what keeps cells together in multicellular organisms. Cells adhere to each other, to extracellular matrices, and to the substratum. Biochemical analyses of these processes have suggested some of the types of surface molecules which may be involved, but definitive evidence must rely on effective reconstruction of functional membranes or genetic alteration of the pertinent genes. Together these approaches may give us a better understanding of how cells sort out and form tissues during development.
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  • 46
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 99-115 
    ISSN: 0192-253X
    Keywords: differential allelic expression ; Zea mays ; isozyme ; endosperm ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The timing of gene expression in the endosperm of developing F1 maize kernels was investigated. Zymogram analysis revealed the presence of maternally derived allelic gene products on all days investigated, but activity of paternally derived allelic gene products is not detectable until days 6-8 postpollination, depending on the particular cross used and the enzyme investigated. This pattern holds true for eight different isozymes of five different enzyme systems, including catalase, alcohol dehydrogenase, glutamate-oxaloacetate transaminase, endopeptid́ase, and aminopeptidase. An increase in specific activity for catalase, alcohol dehydrogenase, and endopeptidase correlates precisely with the day of visualization of the paternally derived allelic gene product on the zymograms. Rocket immunoelectrophoresis confirms a dramatic increase in catalase and alcohol dehydrogenase protein levels on the day the paternally derived allelic gene product is first detected on zymograms. Appropriate crosses utilizing three different allelic variants revealed the presence of enzyme of maternal plant origin within the endosperm prior to day 6 postpollination.Maize kernels were cultured in vitro on an agar-based medium as early as 3 days postpollination. Using medium supplemented with actinomycin D or cycloheximide, it was possible to localize the critical time periods for transcription and translation of the paternally derived allele in the F1 hybrids. For aminopeptidase (AMP-1, AMP-3) and endopeptidase (ENP-1), transcription occurs as early as 3-4 days postpollination, and translation of the transcripts starts at about 4-5 days postpollination. Although the evidence is indirect, it is likely that the maternally derived allele of the F1 kernels is activated (ie, begins transcribing) synchronously with the paternally derived allele during this early developmental time period.
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  • 47
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    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 48
    ISSN: 0192-253X
    Keywords: dedifferentiation ; Dictyostelium ; aggregation ; mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: During slime mold development, cells acquire the capacity to rapidly recapitulate morphogenesis in roughly a tenth the original time. When developing cells are disaggregated and refed, they completely loss this capacity in a rapid and synchronous step referred to as the “erasure event.” The erasure event sets in motion a program of dedifferentiation during which developmentally acquired functions are lost at different times. In this report, we describe the phenotype of HI4, which is a mutant partially defective in the dedifferentiation program but normal in all aspects of growth, morphogenesis, and rapid recapitulation. HI4 cells progress through the erasure event, losing in a relatively normal fashion (I) the capacity to rapidly recapitulate later stages of morphogenesis, (2) the capacity to release a cAMP signal, and (3) the capacity to respond chemotactically to a cAMP signal. However, erased HI4 cells abnormally retain the capacity to rapidly reaggregate, even though they have lost chemotactic functions. Erased HI4 cells also abnormally retain EDTA-resistant cohesion (contact sites A) and the surface glycoprotein gp80. It appears that erased HI4 cells rapidly reaggregate owing to random collisions followed by tight cell cohesion.
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  • 49
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    Chichester [u.a.] : Wiley-Blackwell
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 50
    ISSN: 0192-253X
    Keywords: Neurogenesis ; D. melanogaster ; Gene cloning ; Molecular genetics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Genetic analysis has suggested that neurogenesis in D melanogaster is under the control of a small number of genes. We have initiated a molecular study of the genes involved in this developmental event and started our analysis with the Notch locus, which is one of the best characterized loci in D melanogaster in terms of its genetic structure and developmental effects. In this paper we report on the molecular characterization of the Notch locus.We describe the molecular cloning of Notch and present evidence that the entire locus is defined by approximately 40 kb of genomic DNA. The transcriptional activity of these sequences during development has been examined and the results indicate that an approximately 10.5-kb-long poly A+ RNA is essential for wild type Notch activity. Mapping of this RNA within the physical map of Notch indicates that it is the processed product of an approximately 40-kb primary transcription unit spanning the entire Notch locus. More detailed analysis of the 10.5 kb RNA localizes several exons and identifies a small repetitive sequence that seems to be present in the mature Notch transcript. Structural details of a selected number of Notch locus mutations are presented and discussed. Preliminary data on the molecular structure of Notch-homologous DNA sequences in closely related species are also presented.
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  • 51
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 333-339 
    ISSN: 0192-253X
    Keywords: Drosophila ; chromosome ; polyteny ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A 315 kb walk in the genetically well characterized rosy region of the Drosophila chromosomes permits a molecular analysis of chromosome organization. Polytene chromosome bands in this region range from less than 7 kb to about 160 kb and the level of DNA replication is constant within bands and among bands and interbands. A good numerical and topographical correspondence is found between chromomeric units and genetic units.
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  • 52
    ISSN: 0192-253X
    Keywords: retrovius ; chromosomal evolution ; feline genetics ; somatic cell genetics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A combination of technical advances (most notably heterologous cell fusion, high resolution G-banding, and molecular cloning) has contributed to an accelerated advance in genetic analysis in mammals. The present human genetic map contains over 400 gene assignments and the map is growing rapidly as each new molecular clone or immunological reagent is developed. In our laboratory, we have developed a panel of rodent X human somatic cell hybrids that have been utilized in chromosome assignment of several classes of genes including oncogenes (ras, raf) and endogenous human retroviral sequences (ERVL, 2, etc). Using similar techniques, a biochemical genetic map of the domestic cat has been derived. The cat has 19 chromosome pairs and, to date, 40 genes have been mapped to 16 linkage or syntenic groups. Comparison of linkage relationships between homologous enzymes has revealed a striking conversation of chromosomal linkage association between cat and man. A comparison of syntenically homologous, highly extended high resoultion G-banded chromosomes between the two mammalian families revealed that 20-25%, by length, of the human karyotype can be precisely aligned (chromomere to chromomere) between cats and man despite the evolutionary divergence of the species nearly 80 million years ago.Moderately repetitive families of retrovirus-related DNAs exist within the feline and the human genomes. We have isolated molecular clones of several members of the feline RD-114 retrovirus family from a genomic library of normal cat cellular DNA. The endogenous sequences analyzed were similar to each other in that they were colinear with RD-114 proviral DNA, were bounded by long terminal redundancies, and conserved many restriction sites in the gag and pol regions. Several sequences were apparently deleted, relative to the previously characterized inducible RD-114 genome. The env regions of a number of endogenous RD-114 sequences examined were substantially deleted or diverged; a subset of these sequences contained information at the position of the env region that was not homologous to inducible RD-114. The RD-114 virogenes were dispersed to several cat chrosomes that were localized using a panel of rodent x cat somatic cell hybrids. A comparison of the genetic properties of endogenous human retroviral sequences revealed several similarities between the human and feline status of endogenous retroviruses.
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  • 53
    ISSN: 0192-253X
    Keywords: Drosophila ; small heat-shock protein genes ; ecdysterone ; regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The four small heat shock protein genes of Drosophila are tightly linked at the level of DNA, and are coordinately regulated. In cultured cell lines their expression is induced by high temprature shock and by physiological doses of ecdysterone. In vivo, small heat shock gene expression is developmentally regulated. Using recombinant DNA clones we have characterized and compared small hsp gene induction in response to the two independent stimuli.
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  • 54
    ISSN: 0192-253X
    Keywords: catalase ; Zea mays ; gene regulation ; temporal genes ; development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The catalase (H2O2:H2O2 oxidoreductase; E.C.1.11.1.6; CAT) gene-enzyme system in Zea mays L (maize) represents an ideal model for studying the molecular basis of developmental gene regulation in higher eukaryotes. This system comprises a family of structural genes that are highly regulated, both temporally and spatially, during maize development.In maize, there are four distinct forms (isozymes) of catalase that are readily discernible by convetional separation procedures. Three of the catalases have been studied in detail from a genetic and biochemical viewpoint. The catalases CAT-1, CAT-2, and CAT-3 are encoded by the distinct, unlinked genes Cat1, Cat2, and Cat3, respectively. Each of the structural genes is highly regulated both spatially and temporally in its expression. Cat1 is expressed primarily in the endosperm, aleurone, pericarp, and scutellum of developing kernels, and in the root, shoot, and scutellum of very young seedlings. Cat2 is expressed primarily in the scutellum and leaf during postgerminative sporophytic development. Cat3 is expressed, for the most part, in the shoot and pericarp of young seedlings.A number of regulatory variants have been recovered that affect the developmental program of expression of the catalases. Analysis of one variant allowed for the identification of a temporal regulatory gene (Car1) that specifically alters the developmental program of the Cat2 structural gene by acting to regulate the rate of CAT-2 protein synthesis. Cat1 has been mapped on chromosome 1S, 37 map units (m.u.) from the Cat2 structural gene. Another variant line has been isolated which lacks expression of the Cat2 gene in its tissues at all stages of development. Isolated polysomes from this line (A16) were translated in vitro, and the products were immunoprecipitated with CAT-2-specific antibodies. No CAT-2 was detectable in the A16 labeled immunoprecipitates, whereas CAT-2 was readily detected in the normal line, W64A, under similar conditions.The temporal and spatial expression of the Cat structural genes is not only influenced by genetic factors (as above), but is also responsive to exogenously applied environmental signals: light, hormones, and temperature. The mechanisms by which such signals specifically affect CAT-2 expression will be discussed.
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  • 55
    ISSN: 0192-253X
    Keywords: mRNA structure ; initiation of protein synthesis ; ribosome gel electrophoresis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A method is described for the experimental determination of the secondary structure of RNA using enzymatic cleavage data coupled with computer analysis. The structure-specific enzymes S1 nuclease and cobra venom ribonuclease are used to locate nonpaired and basepaired nucleotides, respectively. Computer techniques that utilize the enzymatic susceptibility information to generate a minimum free-energy structure are used to obtain secondary structure models. A second method, using acrylamide-agarose gel electrophoresis, is described for the determination of the relative protein synthesis initiation rates of endlabeled eukaryotic mRNAs. These methods are applied to the rabbit globin mRNAs as an example of a general approach for relating mRNA structure and function. A discussion of the role of messenger RNA structure in the regulation of translation is included with an emphasis on studies of development.
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  • 56
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 451-451 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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  • 57
    ISSN: 0192-253X
    Keywords: Drosophila ; electrophoretic variation ; quantitative variation ; ecology ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Electrophoretic variation at three enzyme loci-alcohol dehydrogenase (Adh), glycerophosphate dehydrogenase (Gpdh), triosephosphate isomerase (Tpi)- is compared in Australian Drosophila melanogaster populations at three levels of spatial heterogeneity; among breeding sites, within populations, and between populations at the geographic level. Heterogeneity at the breeding site level greatly exceeds that among adults within populations, indicating greater intermixing at the mobile adult stage than at the developmentally immature and less migratory larval stage. Heterogeneity at the microspatial level is large relative to the geographic level at two of these loci.Spatial patterns of variation in ecological phenotypes are also considered. It is argued that electrophoretic variants may contribute little to an understanding of this quantitative variation, and that a more useful approach in ecological genetics is to consider ecological phenotypes as primary data.
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  • 58
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    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 21-29 
    ISSN: 0192-253X
    Keywords: agouti locus ; embryonic lethal ; ax ; lethal nonagouti ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The time and mode of action of the homozygous ax gene, lethal nonagouti, has been investigated on the inbred AX/Pa background. Heterozygotes were mated inter se to produce 25% homozygous embryos and heterozygotes were mated with homozygous, nonagouti mice to provide control litters. Comparisons of the frequency of mating success, the ratio of implantation sites to ovarian ovulation sites, and the average litter sizes between experimental and control matings all indicated that ax/ax embryos are not lost prior to implantation. Histological examination of pregnant uteri indicated that ax/ax embryos are first evident as abnormal blastocysts at 4.5 days post coitum (pc). These implant and develop to varying degrees, some differentiating trophoblast giant cells and a primitive endoderm layer. Growth is retarded and only small, disorganized clumps of tissue remain by 7.5 and 8.5 days pc. The time and mode of gene action of lethal nonagouti is thus different from its allele, lethal Yellow.
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  • 59
    ISSN: 0192-253X
    Keywords: catalase ; Drosophila ; development ; turnover ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ontogenetic and tissue-specific expression of catalase (E.C. 1.11.1.6) has been determined in a wild type strain of Drosophila melanogaster derived from a natural population. Two distinct peaks of activity are observed during development with the first peak occurring in late third instar larvae just prior to puparium formation, and the second and larger of the two peaks occurring during metamorphosis. These peaks of catalase activity are coincident with the two major peaks of ecdysone titer. Of the tissues assayed, larval malpighian tubules, gut, and fat body demonstrated the highest specific activities. Adult abdomen exhibited a two- to three-fold higher specific activity than either head or thorax. Of the abdominal tissues assayed, malpighian tubules and abdominal wall had the highest specific activities. Malpighian tubules were the only sexually dimorphic tissue with respect to catalase activity and are apparently largely responsible for an overall increase observed in female abdominal activity. Catalase-specific CRM levels parallel the enzyme activity levels indicating that these tissue-specific activity differences reflect differences in the rate of accumulation of catalase molecules.Turnover studies employing the catalase inhibitor 3-amino-1,2,4-triazole were conducted on head, thorax, and abdomen of male adult flies. Rates of catalase degradation were similar in the three body segments with a slightly higher rate in abdominal tissue. Therefore the different steady state levels observed largely reflect different rates of catalase synthesis.
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  • 60
    ISSN: 0192-253X
    Keywords: behavioral mutation ; Drosophila ; flightlessness ; temperature sensitive ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutations in 13 genes with temperature-sensitive (ts), flightless phenotypes have been examined. All hop and fly well when raised at the permissive temperature, but fly poorly, or not at all, when raised at the restrictive temperature. The mutations were divided into three groups on the basis of their temperature-sensitive periods (TSPs) for flightlessness. The TSPs for mutations at five loci, fli-C1, D1, E1, I1, and shak A1, in the first group are confined to 24 to 48 hr interval during early pupal development. Mutations in the second group, including eag101, fli B1, and futs1 have continuous TSPs 3 to 4 days in length, extending from late larval through the early pupal stages. The flight TSPs for mutations in the third class, including fli J1, fli K2, flrd H3, and flrd N1, are almost continuous, and span most of the larval and pupal periods. Many of the mutations have pleiotropic phenotypes, including semilethality and lethality, and wing posture and cuticle abnormalities, with discernible TSPs. One of the more intriguing pleiotropic phenotypes is the ts optomotor response exhibited by fli J2, the TSP for which extends from late larval through late pupal stages.
    Additional Material: 12 Ill.
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  • 61
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 4 (1983), S. 143-143 
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 62
    ISSN: 0192-253X
    Keywords: tetrahymena ; mating type ; differentiation ; macronucleus ; starvation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mating type differentiation in Tetrahymena thermophila is known to regularly involve stable hereditary alterations at a single chromosomal locus in the somatic (macro)nucleus. This differentiation is directionally affected by the temperature at which new macronuclei develop after fertilization. We now report large and predictable effects of delayed refeeding of conjugating pairs upon mating type differentiation, particularly among mat-2 homozygotes. The mating types whose frequency is affected the most are IV, VI, and VII, a set different from that most affected by temperature. We interpret our observations to reveal the existence of a second system which can participate in mating type differentiation, with different specificity from the system influenced by temperature under conditions of early refeeding of conjugating pairs. These observations enrich the phenomenology surrounding mating type differentiation in T thermophila and provide additional, easily controllable experimental conditions for the manipulation of mating type frequencies.
    Additional Material: 4 Ill.
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  • 63
    ISSN: 0192-253X
    Keywords: maternal effects ; Polycomb locus ; Drosophila ; homoeosis ; Enhancer of Polycomb ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A mutation or deficiency of the Enhancer of Polycomb (E(Pc)) locus acts as a dominant enhancer of the adult mutant phenotypes of a group of similar homoeotic loci (Polycomb, Polycomblike, extra sex comb, and lethal(4)29). The E(Pc) mutation has a recessive lethal effect, and homo- and hemizygotes die as late embryos or larvae which appear cuticularly normal. E(Pc) also acts as a dominant enhancer of the embryonic homoeotic syndromes associated with Polycomb. Polycomblike, and lethal(4)29 mutations: its effect on the extra sex comb syndrome has not been effectively evaluated. At least for the interaction with Polycomb mutations, evidence is presented that the Enhancer of Polycomb locus has a maternal as well as a zygotic effect, and that its effect on Polycomb expression is not at the level of transcription. We suggest that the Enhancer of Polycomb locus acts specifically to regulate the activities of this set of homoeotic loci, and that E(Pc) recessive lethality results from noncuticular homoeotic defects which arise as a consequence of their reduced activity. In the context of this hypothesis, no present data allow us to distinguish whether Enhancer of Polycomb is a nonhomoeotic locus regulating the function(s) of Polycomb and related genes or is itself a homoeotic locus.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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